This invention relates generally to a means for trickle charging a battery in an electronic device, and more specifically to a means for acoustically charging a battery in a device having a liquid crystal display or other acoustic port.
Portable, or xe2x80x9claptopxe2x80x9d, computer systems are rapidly developing the capabilities of conventional desktop or floor mounted personal computer systems. Many peripherals are being integrated into laptops, including hard disks, floppy disks, backup drives, and modems. The displays in the portable computer systems are becoming much more elaborate and readable. The pixel count on the standard liquid crystal displays (LCD""s) utilized is increasing, as is the viewing angle. The use of backlighting allows use of LCD""s in low light environments and improves the contrast ratio of the display. More complex circuitry is being installed in the portable computers to support these improved peripheral devices and to support the increased speeds and capabilities of the microprocessors utilized in the portable computer systems.
The various peripheral devices and high-speed circuitry mentioned above consume large amounts of power when operating. This has made it very difficult to provide all the possible functionality, while maintaining an acceptable battery life, when the portable computer system is battery powered. CMOS components helped to reduce the power consumption, but even the use of CMOS technology is insufficient at the clock speeds and performance levels of available circuitry. Therefore, a dilemma exists between providing less functionality with longer battery life or greater functionality with less battery life.
Several alternatives are in use to resolve this problem. For example, the IBM PC Convertible included a switch which the user could press to place the computer system in a standby mode, but user action requirement limited its use to instances where the user remembered to depress the switch. Screen savers saved power and prolonged the life of the display. A hard disk unit was developed which reduced the power consumption by controlling electronics to turn off the read channel circuitry until servo bursts were expected. While these alternatives did provide some relief, they were not complete solutions to satisfactorily resolve the dilemma.
There have been attempts at alternative charging systems. For example, U.S. Pat. No. 5,838,138, issued to Henty, discloses a manual method of charging by depressing the keys on the keyboard and converting the mechanical energy into electrical energy. While this is a viable solution, it is cost prohibitive. On the standard computer keyboard, there are over 66 keys. A computer using this technology would thus require over 66 xe2x80x9cmini-chargersxe2x80x9d. This can get expensive.
There is therefore a need for a novel means of providing charge current to a battery to increase battery life.